Mental illness is a frequent talking point in the wake of mass shootings in our country. Politicians refer to the shortcomings of our mental health system and promise to deliver legislative reforms. Media coverage often suggests that if the shooters had been in treatment, these tragedies might never have occurred.

But our national conversation usually ends there. We rarely talk about the realities of identifying dangerous patients and the difficult decisions that mental health providers face in these scenarios.

As a resident physician in psychiatry, I've already seen a number of these cases in my training. Each one leaves its mark. It's hard to sit across from a patient who is threatening to kill someone. These are some of the darkest moments in patient care.

Here's an example of what might happen. A woman visits a psychiatrist because she's been hearing voices. During the appointment, the psychiatrist asks about the voices and how the patient has been dealing with them.

The woman states that the voices remind her of colleagues from work. In fact, the patient says she has come to hate her coworkers for tormenting her and, if she were to find out which ones are responsible, she would kill them.

What should the doctor do?

It’s a decision with profound ethical and legal considerations. Under these circumstances, clinicians often follow the "Tarasoff rule." In 1974, a California Supreme Court case—Tarasoff v. Regents of the University of California—transformed the practice of medicine when justices ruled mental health providers have a duty to break patient-doctor confidentiality if the patient expresses threats against others.

In that case, a patient had disclosed thoughts of killing a female acquaintance named Tatiana Tarasoff to his psychotherapist; the therapist warned local authorities, who interviewed the patient and felt he was not a threat. However, no one warned the woman or her family. The patient soon after stabbed Tarasoff to death, and her parents later sued the therapist for malpractice for not warning them. The case ended up in the California Supreme Court, which ruled in the parents' favor.

In the decades since, dozens of states have adopted this standard, mandating mental health providers take steps to protect those threatened by patients.

The Tarasoff rule makes this duty to protect seem straightforward. If a patient expresses a threat against someone, the health care provider should attempt to get in touch with that person and alert local authorities. In most states, doctors and other authorities can place patients they feel to be imminently dangerous on an involuntary psychiatric hold to complete a mental health evaluation in the hospital.

Yet these situations aren't always so simple. What if the patient was joking? Sometimes, patients don't name anyone specifically, as in the hypothetical scenario earlier in the column. The threat might be conditional, depending on something that may or may not happen in the future.

Writing for the majority opinion in the Tarasoff decision, Justice Mathew Tobriner famously concluded, "the protective privilege ends where the public peril begins." But clinicians have to be careful when deciding to carry out this duty; breaking patient-doctor confidentiality can just as easily ruin the patient's life.

Take the example of Jack Garner, a former police officer profiled in the New York Times Magazine. During the 1990s, he underwent therapy to sort out anger issues and work-related stress; however, after Garner casually vented thoughts of harming work colleagues who had frustrated him, his therapist alerted Garner's coworkers at the police station.

Garner's life subsequently fell apart. He was fired from his job and ostracized in his community. He lost his house and suffered marital problems. He eventually sued the therapist for malpractice in breaking patient-doctor confidentiality; a jury agreed with Garner, awarding him $280,000 in damages.

Did the therapist save the lives of Garner's coworkers? It's impossible to know. That's why relying on mental health providers to predict violence is so tenuous. After all, the overwhelming majority of patients with mental health issues are non-violent. Research suggests less than five percent of violence in the U.S. can be attributed to major mental illness, and psychiatrists oftencan'tpredict which patients may later become violent.

As mental health providers, we try to assess these risks as best we can, asking carefully about threatening statements, reviewing past behaviors, and consulting colleagues for assistance. Still, at the end of the day, we can't know what our patients are going to do when they walk out the door.

The duty to protect is a heavy burden in medicine, equally powerful as it is uncertain. When health care providers pick up the phone to carry out this role, we often do so with trembling hands, wondering if we're doing the right thing.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.

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